When in cooling mode water drips out upper drain tube. Is this standard or should moisture be exhausted with the hot air?

NO
the water is condensation from the humidity in the air turning to water on the cold evaporator core
normally it drips into a tray and drains away outside
if it is inside ( running down the walls it indicates
the drain hole and tube is blocked or the evaporator core is covered in gunk and holding the water up and not dripping where it is designed to
Call an accredited ac specialist shop to clean the fins and drain tube

Condensate drain plug? New to me. Remove the plug and put a 5 gal. bucket to catch the water and remember to drain the bucket, so the furnace won't trip.
When hot plenum is not set hot enough, moisture will condensate on the heat exchanger. This moisture is acidic. It could be your hot plenum temperature needs to be raised to avoide frequent moisture problem.
By the same token, heating and air cooling removes moisture from the air and air needs moisture to feel warm or cool. Dry air is not desired.

Could be the drain tube is partially clogged. It is usually located on the fire-wall or down towards the floor pan under the car. It is usually close to where the A/C lines go thru the fire-wall. About 1/2 inch diameter sticking straight out but may have a 90 degree elbow pointing down.
Also, it's been extra hot and humid all over and moisture could be freezing inside the unit when on MAX A/C, then suddenly melting when switched to normal. This opens the outside air door and allows warm/hot air into the unit instead of recirculating the cold air inside the car. The drain may not be able to handle a large, sudden quantity of water.
Perform a "driveway" test. Open the hood, start engine and run the A/C on normal with the windows or doors open. Locate the drain tube by looking for water dripping. Once located twist 2 or 3 pipe cleaners together and verify the tube is clean. Then close the doors/windows and switch to MAX A/C. Check for water dripping. If it stops dripping, water is freezing inside and now you know why!

Could be the drain tube is partially clogged. It is usually located on the fire-wall or down towards the floor pan under the car. It is usually close to where the A/C lines go thru the fire-wall. About 1/2 inch diameter sticking straight out but may have a 90 degree elbow pointing down.
Also, it's been extra hot and humid all over and moisture could be freezing inside the unit when on MAX A/C, then suddenly melting when switched to normal. This opens the outside air door and allows warm/hot air into the unit instead of recirculating the cold air inside the car. The drain may not be able to handle a large, sudden quantity of water.
Perform a "driveway" test. Open the hood, start engine and run the A/C on normal with the windows or doors open. Locate the drain tube by looking for water dripping. Once located twist 2 or 3 pipe cleaners together and verify the tube is clean. Then close the doors/windows and switch to MAX A/C. Check for water dripping. If it stops dripping, water is freezing inside and now you know why!

As long as you dont cram or force anything up the drain tube, you'll be fine. No, there is no easy way to get to the evaporator area under the dash. There are a lot of fasteners and drilling and cutting is required.

Could be the drain tube is partially clogged. It is usually located on the fire-wall or down towards the floor pan under the car. It is usually close to where the A/C lines go thru the fire-wall. About 1/2 inch diameter sticking straight out but may have a 90 degree elbow pointing down.
Also, it's been extra hot and humid all over and moisture could be freezing inside the unit when on MAX A/C, then suddenly melting when switched to normal. This opens the outside air door and allows warm/hot air into the unit instead of recirculating the cold air inside the car. The drain may not be able to handle a large, sudden quantity of water.
Perform a "driveway" test. Open the hood, start engine and run the A/C on normal with the windows or doors open. Locate the drain tube by looking for water dripping. Once located twist 2 or 3 pipe cleaners together and verify the tube is clean. Then close the doors/windows and switch to MAX A/C. Check for water dripping. If it stops dripping, water is freezing inside and now you know why!

We have the some model air handler, the same problem, are also in Phx AZ. The problem presented itself in July a few days after a heavy monsoon rain and there is still humidity in the air. Shouldn't this unit have a condensation pan? We can't see our because it is all closed up (drywalled in ) but we assumed the drip line lead to a drain since the bathroom is right next to it. Do all these air handlers come with pans?

Could be the drain tube is partially clogged. It is usually located on the fire-wall or down towards the floor pan under the car. It is usually close to where the A/C lines go thru the fire-wall. About 1/2 inch diameter sticking straight out but may have a 90 degree elbow pointing down.
Also, its been extra hot and humid all over and moisture could be freezing inside the unit when on MAX A/C, then suddenly melting when switched to normal. This opens the outside air door and allows warm/hot air into the unit instead of recirculating the cold air inside the car. The drain may not be able to handle a large, sudden quantity of water.
Perform a "driveway" test. Open the hood, start engine and run the A/C on normal with the windows or doors open. Locate the drain tube by looking for water dripping. Once located twist 2 or 3 pipe cleaners together and verify the tube is clean. Then close the doors/windows and switch to MAX A/C. Check for water dripping. If it stops dripping, water is freezing inside and now you know why!

That's what airconditioners do the remove heat and in the process they end up producing some condensation which needs to drain through the drain tube in order to keep the Air conditioner from flooding itself, PLEASE NOTE: The hotter the weather the more drainage you will notice.

Thumbs Up if helpful, Feedback is Appreciated!!!

Normally, an Air Conditioner removes water from the air and that water condenses on the coils of the inside section that does the cooling. The water condenses on the cooling coils just like moisture condenses on the outside of a glass of ice water.
This excess water drains out of the cooling section through a "drip tube" and is supposed to drain outside of the house, or a drainage system. Your "drip tube" has either not been installed (if it is a brand new installation), has separated and water is now dripping into the house instead of outside of it. Or it is clogged. This happens when algae builds up inside the "drip pan". If that is the case, you can purchase "algaecide" tablets which kill the algae that is clogging the drip pan and preventing water from draining out through the drip tube. These tablets can be found in many hardware stores, refrigeration supply companies, or even Walmart. You can put a tablet inside the pan. (You will have to remove the cover of the unit). You can often use a little bit of Bleach and that will act as an algaecide. Hope this helps,
Best, Mark

Hello Cheryl, what they are talking about is a drain. As air conditioners run they collect moisture from the air on the evap(in cooling mode) or condenser ( in heat mode). This moisture will run off the part and flow into the tray. In the cooling mode, the moisture is slung onto the condenser to help cool it down, thus be more effective. I always recommend once a year remove the unit and clean all the coils and oil the fan motor. Household oil will work for this. During this cleaning find and clean out the drain. If it gets clogged that water can run back into the home. The PC pipe is sometimes attached to the unit to direct the water to a designated place. These units are common in hotels and they use the pipe to keep the water from dripping on the guest as they walk under the windows. Hope this helps.